“Cryptogenic Drop Attacks” revisited – evidence of overlap with Functional Neurological Disorder
Ingrid Hoeritzauer 1 MRCP, Alan Carson1, 2,3 MD FRCPsych FRCP, Jon Stone 1,3 MDPhD FRCP
1Centre for Clinical Brain Sciences, University of Edinburgh, UK2 Department of Rehabilitation Medicine, NHS Lothian, Edinburgh, UK 3Department of Clinical Neurosciences, Western General Hospital, Edinburgh, UK
Corresponding author:
Jon Stone
Consultant Neurologist and Honorary ReaderDepartment of Clinical NeurosciencesWestern General Hospital, Edinburgh, EH4 2XU, UKT: +44 (0)131 5371167F: +44 (0) 131 537 1132E: [email protected]
Email Address for other authors: [email protected], [email protected]
Running Title: Cryptogenic drop attacks
Abstract word Count: 250
Word Count (excluding abstract, tables, references): 3682
Tables: Three (two additional supplementary tables) Figures: One
References: 40
Key Words: 1. Drop attacks 2. Cryptogenic 3. Psychogenic 4. Non-epileptic 5. Functional Neurological Symptom Disorder
Key clinical Points included in supplementary data
ABSTRACT
OBJECTIVE
In their 1973 BMJ paper ‘ Cryptogenic Drop Attacks’, Stevens and Matthews described 40,
mostly middle aged, female patients with drop attacks of unknown cause. Although clinically
common, there has been little on this topic since. We aimed to determine clinical features,
comorbidity and outcome of patients with drop attacks.
METHODS
We carried out a retrospective review of patients with cryptogenic drop attacks seen
consecutively by one clinician (JS) between 2006 and 2016. Demographics, phenomenology,
duration and frequency of attacks, attack description and comorbid diagnoses were recorded.
Patients were followed up with a notes review.
RESULTS
83 patients with cryptogenic drop attacks were predominantly female (89%,n=79) mean age
44yrs. The majority (93%,n=77) could not remember the fall itself and almost half (43%,
n=36) experienced prodromal dissociative symptoms. Mechanical trips or syncope preceded
drop attacks, historically, in 24% (n=20) of cases. Persistent fatigue (73%,n=61), chronic
pain (40%,n=33), functional limb weakness (31%,n=26) and dissociative (non-epileptic)
attacks 28% (n=23) were common, with the latter usually preceding or emerging from drop
attacks. At follow-up (88%,mean 38 months), 28% (n=23) had resolution of their drop
attacks. Predisposing (but non-causative) disease comorbidity was found at baseline (n=12)
and follow up (n=5).
CONCLUSIONS
Cryptogenic drop attacks are associated with high frequency of comorbid functional somatic
and functional neurological disorders. Patients commonly have prodromal dissociative
symptoms and in some there was a clear relationship with prior or subsequent dissociative
(non-epileptic) attacks. Some cryptogenic drop attacks may be best understood as
phenomena on the spectrum of dissociative attacks.
Cryptogenic drop attacks
INTRODUCTION
Cryptogenic drop attacks were defined in a seminal paper by Stevens and Matthews in 1973
as falls without warning, without clear cause of loss of consciousness, ‘vertigo or other
cephalic sensation’ and with rapid recovery, occurring predominantly in middle- aged
women[1]. Drop attacks due to various disorders including cardiac, cerebrovascular causes,
vestibular or, most commonly in children, seizure disorders[2–5] have been described since
the early 1900s[4,6–12].
In their study of 40 patients with drop attacks Stevens and Matthews considered various
mechanisms but concluded that this ‘cryptogenic’ presentation was the most common.
Despite their prevalence, estimated at 3.5% of falls in adult women[1], and their potential to
be both embarrassing and fear inducing, no consecutive series of cryptogenic drop attacks in
a predominantly middle age cohort has been undertaken since 1973[6].
Several clinical observations in a series of patients with drop attacks led us to wonder
whether some of them, especially in younger patients, may be considered a subtype of
functional (psychogenic) neurological disorder. We hypothesize that a brief moment of
dissociation, akin to that seen in dissociative (non-epileptic) attacks and/or sudden functional
leg weakness, could be elicited as a conditioned response bound to the experience and
subsequent fear of falling.
We studied the clinical features and outcome of a retrospective consecutive series of patients
with drop attacks to investigate this idea further.
MATERIALS AND METHODS
We searched consecutive outpatient clinic letters for patients with ‘drop attacks’ from one
neurologist (JS) with experience in the diagnosis of dissociative (non-epileptic) attacks,
syncope, seizures and other causes of falls. All patients were referred to the Department of
Clinical Neurosciences, Edinburgh, UK between 2007 and 2016 from one of three sources:
an unselected primary care referral to a general neurology clinic which was randomly
assigned to all general neurologists in the department; a clinic designed for the assessment of
patients with functional disorders; or referred from colleagues due to a known research
interest in patients with drop attacks.
Cryptogenic drop attacks
Patients were included in the study by the authors (other than JS), if they met a modified
version of Stevens and Matthews’ definition of cryptogenic drop attacks: sudden fall to the
ground, not caused by persistent leg weakness, change in posture or head position, nor
accompanied by any vertiginous symptoms. Our modification was to include patients with
intermittent functional leg weakness. We included those who could not remember the fall
itself or who described finding themselves suddenly on the ground but not those who had a
witnessed or perceived loss of consciousness. We included patients who had drop attacks
even if it was not their primary neurological complaint.
We excluded patients with prolonged loss of consciousness or responsiveness and cases when
there was insufficient description of the attack itself. Dissociative (non-epileptic) seizures,
including hypokinetic episodes (psychogenic pseudosyncope) and hyperkinetic episodes,
were differentiated from drop attacks by the presence of reported or witnessed loss of
consciousness or responsiveness with typical positive clinical features seen in those
diagnoses[13]. We also excluded patients whose drop attacks were not cryptogenic, but
included patients where comorbid medical diagnoses may have been contributing to the
clinical picture but did not fully explain it. Drop attacks referred to in this study will refer to
this definition unless otherwise specified.
We retrospectively recorded data on age, gender, duration and frequency of attacks, and
attack description including place, contextual use of medication, alcohol and drugs which
may have caused the drop attack, injury, comorbid diagnoses including structural
pathophysiological, functional somatic, functional neurological and psychiatric disorders
from the medical notes and from JS’s review. Particular attention was paid to the presence of
dissociative symptoms (such as depersonalisation and derealisation), situational triggers, the
circumstances of the first attack and whether attacks changed over time. Comorbid
symptoms and diagnoses were recorded as were radiological and cardiac investigations
performed by the neurologists or other health professionals. We recorded the outcome of
attacks and the development during follow-up of other conditions that, with the benefit of
hindsight, might have explained the drop attacks. Follow up was based on electronic medical
records in the host healthcare board, NHS Lothian, and five additional health boards in
surrounding areas. A UK healthcare board is a connected set of hospitals and outpatient
facilities where patients receive secondary level care. For patients from outside the host
healthcare board and surrounding area, we attempted follow up via an additional, more
Cryptogenic drop attacks
limited, online health record system. Characteristics of patients referred to specialist or
general clinics with drop attacks were compared using two-sided Chi-squared and t-testing.
RESULTS
Participants and Demographics
91 patients with drop attacks were diagnosed and seen by JS between January 2007-July
2016. Eight were excluded (drop attacks due to other causes (n=2), insufficient description of
attacks (n=6)). For the remaining 83 patients, medical records were available for detailed
review. Full electronic patient records documenting all hospital attendances were available
for 67 patients who were referred from within NHS Lothian. Sixteen patients, referred from
outside NHS Lothian underwent more limited notes review.
Of 83 patients, the majority (n= 74, 89%) were female and mean age was 44yrs old (range
12-78yrs). Almost half of the patients (n=37, 44 %) were unselected referrals to a general
neurology clinic (i.e. not specifically to JS), with the others divided almost equally between
the functional disorders clinic (n=20) and those referred by other neurologists (n=26).
Clinical features of attacks.
Some of the key clinical features and their frequency is shown in Table 1
Description of attack. Drop attacks, by definition, occurred suddenly, from standing or
whilst walking. According to their records, the vast majority of patients (93%) could not
remember the fall itself. Patients typically described finding themselves suddenly on the
ground. All patients initially stated they had no warning. However, when asked specifically
about symptoms of dissociation or panic 43% (n=36) of patients described a brief prodrome.
This commonly consisted of depersonalisation and derealisation such as feeling “unplugged”,
“floating” or a feeling of one of their legs not really belonging to them for only a second or
two before the fall.
Twenty-four (29%) patients had soft tissue injuries documented from the falls. More than
half the patients with soft tissue injury had recurrent facial injuries indicating that they did
not put their arms out to protect themselves (n=17). Injuries were also common to the knees
(n=12). Eight patients (9%) had fracture of either a finger (n=3), ribs (n=2), an elbow, toe or
Cryptogenic drop attacks
wrist (all n=1). Unless they were injured, subjects were typically able to get up quickly but
often reported being very embarrassed and worrying about future attacks.
Frequency and duration. The mean duration of drop attacks when first seen at outpatient
clinic was 56 months (range 2-388 months). There were three patterns of attacks: regular
attacks occurring between ten times per day to once per month (n=34), clusters of attacks
with freedom from attacks between clusters (n=6) and infrequent or solitary attacks (n=17).
History of onset of attacks. In almost a quarter of patients (n=20, 24%) the first fall was
reported as different from the subsequent drop attacks and was more likely a simple trip
(n=11), vasovagal syncope (n=4), or associated with feeling generally unwell or dissociation
(n=5).
Triggers. 35% (n= 29) of patients noted drop attacks that were more likely to occur in certain
situations or at certain times. These associations could be with places where they worried
excessively about falling, such as on the stairs, in the bathroom or kitchen or only occurring
outside, in the context of excessive noise or bright lights or when unaccompanied. In two
cases the timing of the falls could be isolated to a short daily period (only occurring between
3-6pm in one patient and between 12-2am in another). Patients frequently expressed constant
background concerns about falling with persistent and significant fear of injury and
embarrassment. Seven patients with regular attacks described transient feelings of relief, or a
feeling that, following an attack, they would be very unlikely to get another one for a few
days, and indeed that prediction would usually be true.
Comorbidities
Comorbid defined pathophysiological diseases at baseline:
At baseline 12 patients (14%) had a potentially relevant comorbidity which may have
increased their vulnerability to drop attacks, by either providing an initial or an ongoing
physiological trigger for the attacks (epilepsy n=4, vertigo n=2, and one each of:
asymptomatic pineal cyst with prior hydrocephalus and static neuroimaging >6years, Chiari
malformation with foramen magnum decompression, basilar tip aneurysm coiling without
evidence of clinical or radiological brainstem damage, left lacunar stroke which caused right
sided weakness, type 1 diabetes but no evidence of hypoglyacemic events, hereditary
hemorrhagic telangiectasia with pulmonary arteriovenous malformation).
Cryptogenic drop attacks
Comorbid functional and/or psychological disorders:
Seventy-five patients (90%) had comorbid functional somatic disorder (n=68, 82%) or
functional neurological symptom disorder (n=48, 51%) which typically overlapped. Somatic
symptoms included: persistent fatigue (n=61, 73%), chronic pain (n= 33, 40%) and irritable
bowel syndrome (n=12, 14%). 58% (n=48) of patients had a comorbid functional
neurological symptom disorder: functional limb weakness (n=26, 31%), dissociative (non-
epileptic) seizures (n=23, 28%), functional movement disorders (n=11, 13%) and other
functional neurological symptoms affecting speech, vision or cognition (n=20, 24%). 23%
(n=19) had episodes of dissociation without loss of consciousness, (i.e. episodes of gradual
zoning out lasting several minutes with interruptibility). 74% of patients with comorbid
dissociative (non-epileptic) seizures had them before the drop attacks and in 26% they
developed after the drop attacks.
Perhaps unsurprisingly, given the unpleasant and random nature of drop attacks, 43% (n= 36)
of patients had a record of anxiety (n=23) or agoraphobia (n=13). Fifteen patients had
depression (18%), three had bipolar affective disorder (one with comorbid schizoaffective
disorder) and one patient had a diagnosis of post-traumatic stress disorder.
We analysed referral bias as an explanation for comorbidity. Patients with drop attacks
referred to an unselected general neurology service (i.e. not referred specifically to JS) had
similarly high levels of functional somatic and functional neurological symptom disorders to
those referred to a functional disorders clinic run by JS (Supplementary Table 1).
Investigations
86% (n=71) of patients had cardiac investigations, 77% (n=64) of patients had CT or MRI
brain imaging and 23% (n=19) of patients had an EEG (Supplementary Table 2). Three
patients had left their general practitioners and their cardiac investigations were impossible to
trace. Of the 71 patients who had documented cardiac investigations, 34 were referred from
either cardiology (n=15) or after normal 24-hour tape (n=19). Others had a mixture of
investigations for cardiac causes of loss of consciousness including ECG plus a mixture of
24-hour blood pressure monitoring, echocardiography, tilt table testing (n=3) and implantable
loop recorder (n=1). Six patients had their typical drop attacks during cardiac monitoring
(n=4 telemetry, n= 1 implantable loop recorder, n=1 pacemaker) without cardiac abnormality.
Cryptogenic drop attacks
Three patients (4%) had neuroimaging abnormalities (n=1 cerebrovascular disease and
atrophy in a patient subsequently diagnosed with frontotemporal dementia (FTD), n=1
previous posterior fossa craniectomy for Chiari malformation, n=1 small vessel ischaemic
changes thought to be non-specific by consultant neuroradiologist).
Prognosis and Treatment
88% (n=73) patients had documented follow up with a mean duration of 38 months (median
29 months, range 0-115months).
During follow up, until the end of July 2016, five patients developed a potentially relevant
disease; dementia n=3 (FTD n=2, Alzheimer’s n=1), ischemic heart disease n=2, prolonged
QTc n=1.
Half of patients’ reported that their drop attacks (n=42, 51%) had either resolved (n=23, no
attacks for at least 6 months) or reduced in frequency by the end of follow up. Almost a
quarter had a static rate of attacks (n=18, 22%), 5% (n=4) were worse and 11% (n=9) had
evolved into dissociative (non-epileptic) seizures.
Only naturalistic data was available on treatment. Ten patients appeared to be treated
effectively for their drop attacks, on the basis of episodes which resolved with distraction
techniques and treatment based on a formulation of their symptoms as a conditioned response
(see below).
Patients without functional comorbidity
Of the eight people without any functional disorder three were male, four had defined
pathophysiological comorbidity (n=1 epilepsy and n=2 FTD, n=1 Hereditary hemorrhagic
telangiectasisa with pulmonary arteriovenous malformation), and one man had events in the
context of alcohol and nicotine excess. Four patients had resolution of drop attacks on follow
up.
DISCUSSION
There are many clearly established causes of sudden falls with preserved consciousness
including simple trips, knee instability, presyncope (and brief vasovagal syncope), arrhythmia
and carotid sinus hypersensitivity, vertigo, cataplexy and colloid cyst of the third ventricle.
Cryptogenic drop attacks
The clinical features of alternate causes of drop attacks are addressed in other articles and
summarized in Table 2 [14–35].
The consideration that cryptogenic drop attacks in the majority of patients may be due to a
pathophysiological disorder causing brief loss of consciousness is warranted [36,37].
Syncope can present without prodrome or with amnesia for the event. Although any type of
syncope can occur without prodrome, arrhythmic cardiac syncope and cardioinhibitory reflex
syncope are perhaps most likely to be associated with a rapid onset of unconsciousness and
are the main pathophysiological differential diagnosis for cryptogenic drop attacks[14,38]. In
patients with syncope, amnesia for the loss of consciousness can be present, occurring in 25-
28% of predominantly older patients (>60yrs) [39]. Additionally, some patients with
provoked syncope may describe dissociative symptoms including an ‘out of body’ experience
(9%). However, we propose that the very brief duration of cryptogenic drop attacks is the key
distinguishing feature. Patients with cryptogenic drop attacks are alert until the start of the
fall and immediately again on hitting the ground, meaning any loss of consciousness or
awareness in drop attacks must be less only a second or two. In any cardiac induced loss of
consciousness it usually takes seconds to lose consciousness and also seconds to regain
it[40,41]. We suggest that the very brief loss of awareness in cryptogenic drop attacks is too
short to be due to cerebral hypoperfusion, whilst accepting that it could be in the realms of a
complicated pre-syncopal episode.
Functional neurological disorders are defined as those in which patients have motor or
sensory symptoms which can be clearly identified as internally inconsistent or incongruous
with disease on the basis of positive signs such as Hoover’s sign or tremor entrainment
test[42]. These highlight the fact that functional motor symptoms are normally maintained by
excessive attention paid to the limb which in turn interferes with normal voluntary movement
[43–45]. The symptoms are experienced as involuntary and may or may not be associated
with psychological comorbidity or prior psychosocial stress.
Research on functional/psychogenic causes of brief loss of consciousness such as
psychogenic pseudosyncope and dissociative (non-epileptic) seizures highlight evidence that
many patients experience dissociative responses as a conditioned response to autonomic
arousal that occurs suddenly and briefly prior to their events [36,37,46]. We have found some
features in our case series to support a hypothesis that cryptogenic drop attacks may, in many
cases, be a functional rather than defined pathophysiological disorder of the nervous system,
Cryptogenic drop attacks
on a spectrum of transient dissociation which includes psychogenic pseudosyncope and
dissociative (non-epileptic) seizures (Table 2, Table 3, Figure 1, also Key Clinical Points).
Features of cryptogenic drop attacks supporting this hypothesis include: 1) cryptogenic drop
attacks are inconsistent with most types of falls in adults in which the fall is usually recalled
[47], 2) a period of loss of awareness too short to represent syncope and only compatible with
dissociation, 3) Brief dissociative symptoms just before or after the event in 43%, 4) the co-
occurrence of clear dissociative (non-epileptic) seizures either before or after drop attack
(28%) or functional limb weakness (31%); 5) Attack clustering and situational attacks in
35%; 6) high comorbidity of fatigue, pain and other symptoms seen in functional
neurological disorders such as dissociative (non-epileptic) seizures[48], 7) Successful
treatment in some patients based on distraction techniques during the prodrome (12%).
Specifically, we propose that in some individuals with cryptogenic drop attacks, the disorder
is best considered a form of brief dissociative attack which then becomes established as a
patterned and conditioned response generated by a fear of falling, either with or without
situational triggers (Table 2 and Figure 1). We hypothesise that patients with a biological or
biopsychosocial vulnerability to drop attacks typically have a triggering event such a simple
fall, trip, syncope or episode of dissociation. Excessive worry about further falls, particular
in inopportune settings, leads to a cognitive representation of the attacks which drives
abnormal self-directed attention and rumination about the possibility of falling. The idea of a
cognitive representation can be conceived both as a consciously processed illness model and
in terms of Bayesian predictive coding, an idea that has been explored in depth in more recent
models of dissociative (non-epileptic) attacks[45],[49],[46]. Our hypothesis is that drop
attacks are at one end of a spectrum of dissociative attacks that includes brief dissociative
episodes with staring and “zoning out”, more prolonged motionless unresponsiveness
(psychogenic pseudosyncope) and episodes with hyperkinetic movements (dissociative
seizures) (Table 3).
We propose that falls occur due to brief loss of awareness secondary to episodes of
dissociation. We hypothesise that this becomes a classically conditioned response and
patients’ falls become associated, in some cases, with situational triggers and in some cases
reinforced by a feeling of relief after the fall is over. Some patients’ drop attacks may develop
through operant conditioning with conscious avoidance of stimuli associated with the drop
attacks. This worry about falling can generalize to anxiety or agoraphobia through the
process of ‘chaining’ where more background stimuli are associated with the drop attack.
Cryptogenic drop attacks
Neurological disease in general is a significant risk factor for functional disorder, being a
potent cause of distortion of sensori-motor experience, cognition and anxiety[50,51]. We
propose that some of the neurological comorbidities described in our series have increased
the risk of functional disorder rather than offering an alternate pathophysiological explanation
in our patients.
Table Two: Features of cryptogenic drop attacks in keeping with a functional disorder
N % Functional Syncope Vertigo Mechanical Cryptogenic
Organic
1. Inability of patients to recall falling 77 93
2. Brief dissociative or panic symptoms just prior to
or after attack
36 43
3. Dissociative (non-epileptic) seizures merging to
drop attacks
23 28
4. First attack recalled as mechanical or simple faint 20 24
5. Long duration of intermittent falls without worsening or development of other symptoms
79 95
6. Co-occurrence with persistent fatigue 61 73
7. Co-occurrence with functional weakness 26 31
8. Attack clustering and situational attacks in some patients (in agoraphobic situations and on stairs).
29 35
9. Feelings of ‘relief’ once the drop attack had occurred, akin to relief seen after some patients with dissociative (non-epileptic) seizures.
7 8
10. Successful treatment of attacks using a model of distraction developed for the treatment of dissociative (non-epileptic) seizures.
10 12
11.Resolution of attacks in patients 23 28
12.Female preponderance 74 89
=possible =likely = very likely
Cryptogenic drop attacks
Table Three: The proposed spectrum of functional (dissociative) attacks or seizures
Cryptogenic Drop Attacks
Dissociative hypokinetic attacks (psychogenic pseudosyncope)
Dissociative (non-epileptic) hyperkinetic attacks
Dissociative ‘absence’ attack
Gender distribution
Predominantly female
Peak age of onset
Mid 40s Late 20s[37,40]
Usually presents to
Cardiology, Neurology
Cardiology Neurology Neurology/Psychiatry
Usual Clinical setting and Prodrome
Patients describe finding themselves suddenly on the ground without apparent loss of consciousness
Long duration episodes of ‘fall down lie still’ (i.e.> two minutes), typically with eyes closed [40]
Episodes of generalized or focal limb shaking, typically with eyes closed and other positive features[15]
Episodes of being relatively unresponsive or staring, with or without experience of unawareness or dissociation
Prodrome and proposed Mechanism
Prodromal dissociative symptoms and arousal in many patientsFearful anticipation increases likelihood of events and attacks may cluster situationally in some
Trigger All may apparently be triggered by initial fall, vasovagal syncope or panic attacks which are different from subsequent drop attacks[16,51]
In our series, recurrent facial soft tissue injuries were more common than the bruised knees
from which drop attacks gain their French name ‘la maladie des genoux bleus’. Injuries have
long been associated with dissociative seizures occurring in 30-40% of case series [52,53].
Drop attacks are not a benign condition either and many of our patients gave up work or had
substantial social and occupational impairment. Comorbid functional neurological disorders
have not been previously described in patients with cryptogenic drop attacks including in
Steven’s and Matthew’s paper. Given that one third of our patients were unselected referrals
to a general neurology service this suggests a genuine association. The absence of comorbid
functional disorders in reported literature may be due to lack of expertise in identifying
functional disorders by non-neurologists seeing these patients or lack of confidence in
making a diagnosis by neurologists. Similar underreporting of psychogenic pseudosyncope is
seen in large cohort studies of syncope [54]. The lack of any in-depth studies of younger
patients with cryptogenic drop attacks since 1973 may also play a role.
Even if the majority of patients with cryptogenic drop attacks can be thought of as attacks
within the spectrum a functional neurological disorder, there are patients in our study in
whom the aetiology of their drop attacks remains cryptogenic. Men were entirely absent
Cryptogenic drop attacks
from the Stevens and Matthews series. They represented 11% of our cohort and are under-
represented even in older drop attack populations [5]. In our study the comorbid defined
pathophysiological risk factors at baseline or follow up was over three times that in men than
women (55% vs. 15%), raising the possibility that mechanisms of drop attacks in men may
have some differences to women. The absence of a comorbid functional disorder should also
signal a warning flag for underlying pathophysiological disorders given the high proportion
(50%) in our eight patients.
We acknowledge significant limitations in this data which we present as hypothesis
generating. This was a retrospective study of consecutive cases seen in routine clinical care
and clinical variables were chosen from this material. There are many variables, including
adverse childhood experience, that we did not collect. Importantly, not all patients were
subject to neuroimaging or cardiac investigation such as 24 hour ECG or EEG. More detailed
investigations such as tilt table testing and specific measures of balance were not applied[55].
It remains the case, that some of these patients may have alternative diagnoses, particularly
syncope. A comparison group with a paroxysmal condition such as neurocardiogenic syncope
would have helped to examine the specificity of some of the proposed associations. JS’s
clinical interest in functional disorders may have biased frequency of comorbidity, although
similar frequencies were seen in unselected referrals to a general neurology clinic. Because
our patients were seen clinically rather than in a research study, physiological and structural
measures of falls, such as dynamic posturography, used in other studies were not routinely
used in our patients. Sixteen of the 83 patients were referred from outside of the health board
which may have led to an underestimate of follow up diagnoses. Data on treatment modalities
and outcomes was insufficient for more in-depth analysis, so was only considered
anecdotally.
Additionally, ideas solidified through the process of seeing patients and some of the questions
asked of the 83rd patient were not the same as those asked of the first. We have endeavored to
make the process as uniform as possible by including only those patients who were seen by
the author JS and excluding patients where the description of the attack could not be judged
by the rest of the research team.
We present our data to support a hypothesis weaved together from the stories of the patients
seen in routine clinical practice. We suggest considering cryptogenic drop attacks in some
patients as a subtype of functional neurological disorder. We propose that brief episodes of
Cryptogenic drop attacks
dissociation, often precipitated by a mechanical fall or faint, perpetuated by fear of falling can
become habitual via a conditioned behavioral response. This could lead to specific treatment
techniques involving education, distraction techniques, overcoming avoidance and graded
exposure to the conditioned stimuli.
A prospective multi-centre controlled study of drop attacks in younger individuals that avoids
the limitation of this case series including tilt-table testing and, where possible, timing of loss
of awareness as well as multiple psychological, physiological and structural measures is
warranted to examine the question of whether cryptogenic drop attacks overlap with
functional neurological symptom disorders or are better thought of, and treated as, functional
drop attacks.
Funding
IH is supported by an Association of British Neurologists/Patrick Berthoud Clinical Research Training Fellowship. JS is supported by an NHS Scotland NRS Career Fellowship.
Note to reviewers who may have seen the abstract for this study (not to be published)
Data on investigations have been updated since an earlier version of this study
Cryptogenic drop attacks
Cryptogenic Drop Attacks
Cardiac Syncope Carotid sinus hypersensitivity
Vestibular drop attacks
Posterior circulation TIA
Chiari malformations
Colloid cyst of the third ventricle
Epileptic drop attacks (including brief focal, tonic or atonic seizures)
Structural cardiac diseases (e.g. atrial myxoma)
Usual Demographics
Women,mid 40s
Rare in childrenOften occurs >60s[38]
M:F ratio 4:1>50yrs[17]
F:M ratio 1-3:1[18]40-60yrs
M>F; >65yrs
F:M ratio 1.3-1.7:1 [19]
30-35yrs
M:F ratio 1.5:1,[20] 30-40yrs
M:F ratio variableChildhood onset[4,21]
F>M60s[22,23]
Frequency UnclearEstimated at 3.5-9% of all falls referrals[1,35]
15% of patients with syncope[24]
10% of population >65yrs old22-68% of older patients with syncope and falls[17],
[5]
190 per 100,000 of the population)[25]
20% of ischemic events[26]
Radiological prevalence 0.77%3% of patients present with drop attacks[3]
0.5-2% of intracerebral tumours[20,27]
2% of patients admitted to national VEEG unit[4]
Estimated at between 0.001-0.28% of the population from autopsy studies[32]
Usual Clinical setting and Prodrome
Patients describe finding themselves suddenly on the ground
Dissociative symptoms pre or post attack
Overlap with dissociative (non-epileptic) attacks
Fearful anticipation increases likelihood of events and attacks cluster situationally
Can occur in any posture
no prodrome or brief prodrome without autonomic symptoms (no nausea or sweating)
Pallor
Rapid recovery after loss of consciousness
Occurs on head turning, shaving, or when wearing a tight collar[38]
Syncope occurs but many patients (20-70%) have amnesia for the syncope and present with falls only [17]
Patients describe a feeling of being pushed to the ground
ORA feeling of the surroundings suddenly moving or tilting causing the fall[34]
Patients often fall in the same direction during each fall
Associated with limb weakness, ataxia and oculomotor palsy[33],[26]
Usually lasts >5minutes[35]
Suboccipital headache, numbness exacerbated by Valsalva maneuversWeakness, numbness, loss of temperature sensation 90% have abnormal signs on examination including hyperreflexia and ‘cape’ sensory loss[3,19]
Symptoms of raised intracranial pressure[27] e.g. headache with nausea and vomiting[20]
Altered GCS
Can be found incidentally
Occur almost exclusively in patients with other neurological abnormalities
Often linked to severe epilepsies in childhood
In parasagittal seizure foci somatosensory auras and generalized seizures usually occur[28].
Most commonly presents with cardioembolic stroke or symptoms of congestive heart failure[23]
Angina, pyrexia and palpitations may co-occur[32]
Table One: Differential Diagnoses of Drop Attacks
Cryptogenic drop attacks
Trigger Often triggered by fall or faint which is different from ongoing drop attacks
More common during exercise
Occurs on head turning, shaving, or when wearing a tight collar
None None Unclear, controversy about link with orthostatic intolerance[29]
None stated Usual triggers for seizures e.g. withdrawal of anticonvulsants
None
Long term outcome
Can resolve spontaneously or be present for years without escalation.
Patients may develop dissociative attacks.
Depends on aetiology. Causes are:Structural heart disease, Brady/tachy-arrhytmias or inherited channelopathies
Over 50% of patients suffer serious injury due to fall
High rate of recurrence
Occurs frequently during the first year of symptoms then spontaneously remits[2]
At increased risk of MI, IHD and stroke
Will usually develop other neurological symptoms
Symptomatic cysts can lead to raised ICP and death if untreated.
>80% of patients treated with microsurgery have a good long term outcome[30],
[20]
Falls can lead to injury
Seizure frequency often high
Life-threatening complications can occur if symptomatic tumors are left untreated
Asymptomatic tumors often have good long term prognosis
Treatment No good evidence
We suggest trials of:Distraction techniques, CBT, physiotherapy
Structural disease and inherited channelopathies: implantable defibrillatorBrady/tachy-arrhytmias: Pacemaker
Pacemaker Conservative management, Intratympanic gentamycin injection[18]
Thrombolysis, antiplatelet agents and management of cardiovascular risk factors.
May require operative management if clinically deteriorating
Symptomatic or large cysts require operation.
Anticonvulsants[21],[31]
Complete surgical excision can be carried out in most cases[22]
Cryptogenic drop attacks
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